In vivo confocal reflectance microscopy of congenital melanocytic nevi

The presence of congenital melanocytic nevi (CMN) is determined in utero. CMN are neural crest-derived malformations, composed mainly of a benign proliferation of melanocytes. The most common method for the classification of CMN is based upon nevus size. Small CMN are defined as smaller than 1.5 cm in diameter, medium-sized CMN are 1.5–19.9 cm, large CMN are over 20 cm in diameter, and very large (i.e., giant CMN) are over 50 cm in diameter. Rational for the size-based classification is that there is an increased risk of developing melanoma, a larger cosmetic impact and a greater surgical complexity with increasing size of CMN. In addition, large and giant CMN are often intermixed with various other neural crest-derived elements such as neural tissue and may be associated with extra-cutaneous malformations such as neurocutaneous melanocytosis, dandy-walker malformation, and vascular anomalies [1].